1. Field of the Invention
The present invention relates to improved access space cover lifting tools. More specifically, the invention relates to a lever-type manual tool for lifting and maneuvering manhole covers and gratings of various sizes away from respective manholes, wherein a freely slidable sleeve mounted on the lever permits a virtually infinite range of adjustments of the distance between the fulcrum and the sleeve, thereby enabling the tool to be used with any size cover while maximizing the available leverage.
2. Related Art
There are a number of manhole cover lifting devices disclosed in the prior art. For example, in one, a lever is combined with scissors-type lifting means for lifting a manhole cover and pivoting the raised cover away from the manhole in a horizontal plane.
In another, a lever-type manhole cover lifting tool is combined with a hydraulic jack, hydraulic cylinder, or pulley cable to facilitate lifting of the cover and thereafter pivoting the cover away from the manhole.
Other devices include manually operated lever-type lifting tools in which one or more points of attachment for a member connected to the manhole cover are fixed along the length of the lever. Flexible chains may be connected between the selected, fixed points of attachment on the lever and lifting elements attached to the manhole cover. However, because the attachment points are fixed, the chain must be adjustable in length to accommodate manhole covers of different diameter. This arrangement is unsatisfactory since it is not possible to maximize leverage, and additional hardware is often required to insure secure attachment of the chain links to the various fixed points of attachment.
Manhole cover diameters may be 34 inches in diameter. Accordingly, there is a need for a manhole cover lifter tool which is simple and easy to use, which maximizes leverage, and which accommodates all manhole cover sizes as well as various grating covers.
A more recent lifting device, U.S. Pat. No. 4,991,893, is limited by the length of the sliding sleeve which is too short for optimum load bearing. The tool lever member is also too short to achieve maximum leverage. Other features include hook members that do not provide adequate gripping of very large and heavy covers.
Other examples of cover lifting devices that are known to the prior art include U.S. Pat. Nos. 5,462,385; 6,520,482; 6,676,111; and 6,964,407.